This invention relates to an apparatus for forming a lead wire of a package which receives semiconductor devices.
Lead wire forming apparatus of the type described is disclosed in Japanese Unexamined Patent Prepublication (Kokai) No. 2.84454/1990. The conventional lead wire forming apparatus comprises a first die, a second die, a third die, a slidable board or base, and a wire pushing member.
The second die is opposed to the first die and is movable to the first die. The second die is for pinching a package and lead wires of the package in cooperation with the first die with protruded portions of the lead wires that are protruded from the first and the second dies.
The first die has a die surface under the protruded portions of the lead wires. The slidable base is slidably supported on the die surface through a ball bearing. The third die is movable to the first die. The wire pushing member is fixed to the third die and is moved together with the third die. The wire pushing member pushes the protruded portions of the lead wires to form predetermined forms with one end portion of the lead wires that are supported on the slidable base when the wire pushing member is moved downwardly.
The protruded portions of the lead wires are pushed by the wire pushing member and formed. The slidable base is moved together with the protruded portions of the lead wires by friction between the slidable base and the protruded portions of the lead wires when the protruded portions of the lead wires are displaced by the wire pushing member.
The first die has an internal die surface which defines an exhaust hole and an exhaust nozzle which is opposed to the slidable base. An air injector is associated with the exhaust hole. The air injector injects compressed air in the exhaust hole to exhaust the compressed air towards the slidable base through the exhaust nozzle. The slidable base is recovered to an initial position by the force of the compressed air which is injected from the exhaust nozzle.
However, inasmuch as the protruded portion of the lead wire has solder on its surface, the solder is easily peeled from the lead wire by the friction between the slidable base and the lead wire. Also, inasmuch as junks of the solder peeled from the lead wire easily enter between the slidable base and the die surface of the first die, the slidable base is hardly capable of moving smoothly. In addition, the lead wires are shorted when the junks of the solder readhere to the lead wires.